diff --git a/crates/obscura-dom/src/lib.rs b/crates/obscura-dom/src/lib.rs
index 6d3d6fc..6ad84be 100644
--- a/crates/obscura-dom/src/lib.rs
+++ b/crates/obscura-dom/src/lib.rs
@@ -7,4 +7,4 @@ pub mod selector;
 pub mod serialize;
 
 pub use tree::{Attribute, DomTree, Node, NodeData, NodeId};
-pub use tree_sink::{parse_html, parse_fragment};
+pub use tree_sink::{parse_fragment, parse_fragment_with_context, parse_html};
diff --git a/crates/obscura-dom/src/tree_sink.rs b/crates/obscura-dom/src/tree_sink.rs
index e116b5a..8720fd5 100644
--- a/crates/obscura-dom/src/tree_sink.rs
+++ b/crates/obscura-dom/src/tree_sink.rs
@@ -246,10 +246,14 @@ pub fn parse_html(html: &str) -> DomTree {
 }
 
 pub fn parse_fragment(html: &str) -> DomTree {
-    use html5ever::tendril::TendrilSink;
-    use html5ever::{parse_fragment, ParseOpts, QualName};
-
     let context_name = QualName::new(None, ns!(html), local_name!("body"));
+    parse_fragment_with_context(html, context_name)
+}
+
+pub fn parse_fragment_with_context(html: &str, context_name: QualName) -> DomTree {
+    use html5ever::tendril::TendrilSink;
+    use html5ever::{parse_fragment, ParseOpts};
+
     let tree = DomTree::new();
     parse_fragment(tree, ParseOpts::default(), context_name, vec![])
         .from_utf8()
diff --git a/crates/obscura-js/js/bootstrap.js b/crates/obscura-js/js/bootstrap.js
index 423bc40..9422a22 100644
--- a/crates/obscura-js/js/bootstrap.js
+++ b/crates/obscura-js/js/bootstrap.js
@@ -24,7 +24,7 @@
     '_isSpecialScheme', '_applyDocQueryEncoding', '_anchorBase',
     '_elemHrefURL', '_setElemHrefPart', '_pad', '_daysInMonth',
     '_isoWeek1Monday', '_inputParseNumber', '_inputFormatNumber',
-    '_htmlAttrName', '_convertNodes', '_elementClassFor', '_wrap', '_wrapEl',
+    '_htmlAttrName', '_convertNodes', '_parseHTMLFragment', '_elementClassFor', '_wrap', '_wrapEl',
     '_resolveUrl', '_registerIframe', '_base64ToUint8Array',
     '_bodyToUint8Array', '_arrayBufferFromBytes',
     '_installWasmStreamingFallback', '_urlParseOp', '_urlSetOp',
@@ -1329,6 +1329,23 @@ function _isSubmitButton(el) {
   return false;
 }
 
+// Parse an HTML string into detached nodes using the actual insertion element
+// as html5ever's fragment context. This preserves table/select parsing rules,
+// comments, text-node order, and foreign-content namespaces without a wrap map.
+function _parseHTMLFragment(html, context) {
+  html = String(html == null ? '' : html);
+  const ns = context && context.nodeType === 1 ? context.namespaceURI : null;
+  const tag = context && context.nodeType === 1 ? context.localName : 'body';
+  const tmp = ns && ns !== 'http://www.w3.org/1999/xhtml'
+    ? document.createElementNS(ns, tag)
+    : document.createElement(tag);
+  tmp.innerHTML = html;
+  const out = [];
+  let child;
+  while ((child = tmp.firstChild)) out.push(tmp.removeChild(child));
+  return out;
+}
+
 class Element extends Node {
   constructor(nid) {
     super(nid);
@@ -1583,20 +1600,33 @@ class Element extends Node {
     return null;
   }
   insertAdjacentHTML(position, html) {
+    // Position is matched ASCII-case-insensitively; an unknown value throws
+    // SyntaxError (both were silent no-ops before). Sibling insertions parse
+    // against the parent's context, child insertions against this element, so
+    // table/select fragments keep the right parsing context (_parseHTMLFragment).
+    const pos = String(position).toLowerCase();
     const parent = this.parentNode;
-    switch (position) {
+    const context = (pos === 'beforebegin' || pos === 'afterend') ? parent : this;
+    switch (pos) {
       case 'beforebegin':
-        if (parent) { const tmp = document.createElement('div'); tmp.innerHTML = html; const children = tmp.childNodes; for (let i = 0; i < children.length; i++) parent.insertBefore(children[i], this); }
+        if (parent) for (const n of _parseHTMLFragment(html, context)) parent.insertBefore(n, this);
         break;
-      case 'afterbegin':
-        { const tmp = document.createElement('div'); tmp.innerHTML = html; const children = tmp.childNodes; const first = this.firstChild; for (let i = children.length - 1; i >= 0; i--) this.insertBefore(children[i], first); }
+      case 'afterbegin': {
+        const first = this.firstChild;
+        for (const n of _parseHTMLFragment(html, context)) this.insertBefore(n, first);
         break;
+      }
       case 'beforeend':
-        { const tmp = document.createElement('div'); tmp.innerHTML = html; const children = tmp.childNodes; for (let i = 0; i < children.length; i++) this.appendChild(children[i]); }
+        for (const n of _parseHTMLFragment(html, context)) this.appendChild(n);
         break;
       case 'afterend':
-        if (parent) { const tmp = document.createElement('div'); tmp.innerHTML = html; const children = tmp.childNodes; const next = this.nextSibling; for (let i = 0; i < children.length; i++) parent.insertBefore(children[i], next); }
+        if (parent) { const next = this.nextSibling; for (const n of _parseHTMLFragment(html, context)) parent.insertBefore(n, next); }
         break;
+      default:
+        throw new DOMException(
+          "Failed to execute 'insertAdjacentHTML' on 'Element': The value provided ('" + position + "') is not one of 'beforeBegin', 'afterBegin', 'beforeEnd', or 'afterEnd'.",
+          "SyntaxError"
+        );
     }
   }
   // Like insertAdjacentHTML but inserts a Text node instead of parsing markup,
diff --git a/crates/obscura-js/src/ops.rs b/crates/obscura-js/src/ops.rs
index 64aad05..37e5cc7 100644
--- a/crates/obscura-js/src/ops.rs
+++ b/crates/obscura-js/src/ops.rs
@@ -391,7 +391,16 @@ fn op_dom_inner(state: &OpState, cmd: String, arg1: String, arg2: String) -> Str
                 dom.detach(child);
             }
             if !arg2.is_empty() {
-                let fragment = obscura_dom::parse_fragment(&arg2);
+                let context_name = dom
+                    .with_node(target, |node| match &node.data {
+                        NodeData::Element { name, .. } => Some(name.clone()),
+                        _ => None,
+                    })
+                    .flatten();
+                let fragment = match context_name {
+                    Some(name) => obscura_dom::parse_fragment_with_context(&arg2, name),
+                    None => obscura_dom::parse_fragment(&arg2),
+                };
                 let import_root = fragment.find_body_or_root();
                 dom.import_children_from(target, &fragment, import_root);
             }
diff --git a/crates/obscura-js/src/runtime.rs b/crates/obscura-js/src/runtime.rs
index 541b336..aa84dde 100644
--- a/crates/obscura-js/src/runtime.rs
+++ b/crates/obscura-js/src/runtime.rs
@@ -1549,6 +1549,61 @@ mod tests {
         assert_eq!(out, serde_json::json!("1|OPTION|choice"));
     }
 
+    #[test]
+    fn insert_adjacent_html_parses_table_fragments() {
+        let mut rt = setup_runtime(
+            r#"<html><body><table id="t"><tbody id="tb"></tbody></table></body></html>"#,
+        );
+        let out = rt
+            .evaluate("(function(){var tb=document.getElementById('tb'); tb.insertAdjacentHTML('beforeend','<tr><td>1</td><td>2</td></tr>'); var tr=tb.firstElementChild; return tr ? (tr.tagName+':'+tr.children.length) : 'NULL';})()")
+            .unwrap();
+        assert_eq!(out, serde_json::json!("TR:2"));
+    }
+
+    #[test]
+    fn insert_adjacent_html_position_is_case_insensitive() {
+        let mut rt = setup_runtime(r#"<html><body><div id="host"><span>base</span></div></body></html>"#);
+        let out = rt
+            .evaluate("(function(){var h=document.getElementById('host'); h.insertAdjacentHTML('BeforeEnd','<b>x</b>'); return h.lastElementChild ? h.lastElementChild.tagName : 'NULL';})()")
+            .unwrap();
+        assert_eq!(out, serde_json::json!("B"));
+    }
+
+    #[test]
+    fn insert_adjacent_html_rejects_invalid_position() {
+        let mut rt = setup_runtime(r#"<html><body><div id="host"></div></body></html>"#);
+        let out = rt
+            .evaluate("(function(){var h=document.getElementById('host'); try { h.insertAdjacentHTML('nope','<b>x</b>'); return 'no-throw'; } catch(e){ return e.name; }})()")
+            .unwrap();
+        assert_eq!(out, serde_json::json!("SyntaxError"));
+    }
+
+    #[test]
+    fn insert_adjacent_html_keeps_leading_comments_in_table_contexts() {
+        let mut rt = setup_runtime(
+            r#"<html><body><table><tbody id="tb"><tr id="row"></tr></tbody></table></body></html>"#,
+        );
+        let out = rt
+            .evaluate(
+                "(function(){var tb=document.getElementById('tb');tb.insertAdjacentHTML('beforeend','<!--m--><tr><td>v</td></tr>');var row=document.getElementById('row');row.insertAdjacentHTML('beforeend','<!--n--><td>x</td>');return Array.from(tb.childNodes).map(function(n){return n.nodeName}).join('|')+';'+Array.from(row.childNodes).map(function(n){return n.nodeName}).join('|');})()",
+            )
+            .unwrap();
+        assert_eq!(out, serde_json::json!("TR|#comment|TR;#comment|TD"));
+    }
+
+    #[test]
+    fn insert_adjacent_html_uses_the_insertion_element_as_context() {
+        let mut rt = setup_runtime(
+            r#"<html><body><div id="d"></div><table id="table"><tbody id="tb"></tbody></table></body></html>"#,
+        );
+        let out = rt
+            .evaluate(
+                "(function(){var d=document.getElementById('d');d.insertAdjacentHTML('beforeend','<tr><td>v</td></tr>');var table=document.getElementById('table');table.insertAdjacentHTML('beforeend','<tr><td>x</td></tr>');var tb=document.getElementById('tb');tb.insertAdjacentHTML('beforeend','<tr><td>y</td></tr>tail');return d.firstChild.nodeName+':'+d.textContent+';'+table.lastElementChild.tagName+';'+Array.from(tb.childNodes).map(function(n){return n.nodeName+(n.data?':'+n.data:'')}).join('|');})()",
+            )
+            .unwrap();
+        assert_eq!(out, serde_json::json!("#text:v;TBODY;TR|#text:tail"));
+    }
+
     #[test]
     fn test_document_title() {
         let mut rt = setup_runtime("<html><head><title>Test</title></head><body></body></html>");